page_title: Airco DH.4
section_title: Civil use
hierarchical_section_title: Airco DH.4 / Operational history / Civil use
caption_attribution_description: English: Airco DH.4, US Airmail
context_page_description: The Airco DH.4 was a British two-seat biplane day bomber of the First World War. It was designed by Geoffrey de Havilland for Airco, and was the first British two-seat light day-bomber to have an effective defensive armament.
  The DH.4 was developed as a light two-seat combat aircraft, intended to perform both aerial reconnaissance and day bomber missions. One of the early aims of the design was for it to be powered by the newly-developed Beardmore Halford Pullinger engine, which was capable of generating up to 160 hp. During its first years of flight, it was tried with several different engines, perhaps the best of which was the 375 hp Rolls-Royce Eagle engine. Armament and ordnance for the aircraft consisted of one 0.303 in Vickers machine gun for the pilot and one 0.303 in Lewis gun on a Scarff ring mounting for the observer. In addition, either a pair of 230 lb bombs or a maximum payload of four 112 lb bombs could be carried.
  The DH.4 first flew in August 1916; less than a year later, it entered operational service in France on 6 March 1917 with No. 55 Squadron of the Royal Flying Corps.
context_section_description: Following the end of the First World War, large numbers of DH.4s and DH.4As were used to operate scheduled passenger services in Europe by such airlines as Aircraft Transport and Travel, Handley Page Transport and the Belgium airline SNETA. G-EAJC of Aircraft Transport and Travel flew the first British commercial passenger service from Hounslow Heath Aerodrome to Paris Le Bourget on 25 August 1919, carrying a reporter from the Evening Standard newspaper and a load of newspapers and other freight. They were used by Aircraft Transport and Travel until it shut down in 1920, while Handley Page Transport and SNETA continued operating the DH.4 until 1921. One aircraft was used by Instone Air Lines until its merger into Imperial Airways in 1924.
  The DH.4 were also used by the Australian airline QANTAS, flying its first airmail service in 1922. Twelve DH.4s forming part of the Imperial Gift to Canada were used for forestry patrol and survey work, spotting hundreds of forest fires and helping to save millions of dollars worth of timber, with the last example finally being withdrawn in 1927.
  
  The U.S. Post Office also adopted the DH-4 to carry air mail. The Service acquired 100 of them from the army in 1918, and retrofitted them to make them safer, denominating them as the DH.4B. In 1919, the DH-4B was standardised by the US Post Office, being modified to be flown from the rear cockpit with a 400 lb (180 kg) watertight mail compartment replacing the forward cockpit. The airmail DH-4B were later modified with revised landing gear and an enlarged rudder. DH-4s were used to establish a coast-to-coast, transcontinental airmail service, between San Francisco and New York, a distance of 2,680 mi (4,310 km), involving night flight, the first services starting on 21 August 1924. The DH-4 continued in Post Office service until 1927, when the last airmail routes were passed to private contractors.
caption: Robertson Aircraft Corp. operated DH-4 mailplane (CAM 2) 1926 at the Historic Aircraft Restoration Museum.
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